1. Field of the Invention
The present invention relates to a seat back of a seat in general and more particularly to a framework of seat back of a vehicle or automotive seat.
2. Description of Prior Art
Reference is first made to FIG. 1 which shows a conventional seat back framework adapted for use in such seat back (SB) of vehicle or automotive seat as shown in FIG. 7, for instance.
This framework is generally composed of an inverted-U-shaped main frame (3), a pair of side brackets (2) (2) each being firmly attached to the respective pair of lateral frame sections (32) (32) of the main frame (3), a support wire member (1) fixed at the upper region of the main frame (3) and a lower transverse frame (33). The main frame (3) is formed by bending a tubular rigid material, for example, into the illustrated inverted-U-shaped configuration.
A pair of side brackets (2) (2) stated above are each of the type having a generally channel cross-section, as shown, and welded at the base end thereof to and along the respective two lateral frame sections (32) (32) in the longitudinal direction, such as to project the free end thereof in the direction forwardly of the main frame (3), i.e. from the forward side at (3F), corresponding to the frontal or forward side of seat back (SB) where the back of an occupant sitting on the seat is to be supported, as understandable from FIG. 7. Specifically, as seen in FIGS. 1 and 2, the base end of each side bracket (2) constitutes a rear flange portion (22) of generally channel cross-section adapted to be embracingly attached about the rearward surface (3B) of lateral frame section (22), whereas on the other hand, the free end of side bracket (2) constitutes a forward flange portion (21) which is curved from the body of side bracket in the direction inwardly of the main frame (3), having a similar channel cross-section to that of the rearward flange portion (22). Thus, as shown, the side bracket (2) is firmly attached, at its rearward flange portion (21), about the rearward surface (3B) of main frame lateral frame section (32) by welding.
The support wire member (1) is generally of the shown configuration extending on a linear line, having two end portions (1B') (1B') situated on the same linear line, though the wire member (1) itself is formed uneven in the main body portion (1A) thereof for the purpose of supporting the two headrest stays (S) (S) (See FIG. 7). This wire member (1) extends transversely of the upper region of main frame (3) and is fixed at the two end portions (1B') (1B') thereof to the respective pair of lateral frame sections (32) (32) of main frame (3). As can be seen from FIG. 2, each end portion (1B') of wire member (1) is welded at (10') upon the forward surface (3F) of the corresponding main frame lateral section (32) and disposed above and distant from the projected sheer upper end (21A) associated with the forward flange portion (21) of side bracket (2). Below such support wire member (1), there lies another support wire member (11) of a rectilinear form which also extends transversely of the main frame (3). This wire member (11) is welded at its both ends to the two lateral frame sections (32). Both two support wire members (1) (11) serve to supportively receive the corresponding inner side of upholding (i.e. 4, 5) as can be seen in FIG. 7.
Designations (SH) denote a pair of cylindrical stay holders fixed on the intermediate frame section (31) of main frame (3), in which are to be inserted and secured the two stays (S) (S) of headrest (HD), respectively, as shown in FIG. 7.
The seat back framework may be placed in and covered with a suitable upholding made of a trim cover assembly (5) and a molded foam padding (4), as shown in FIG. 7, so as to form a predetermined seat back (SB) for vehicle or automotive seat.
However, in the present prior-art framework, referring to FIG. 2, due to a spacing (L) provided between the projected upper end (21A) of side bracket (21) and the main frame lateral section (32), there is naturally created a recession or difference in level, at (R), between that particular end (21A) and the end portion (1B') of support wire member (1). Further, such end portion (1B') of support wire member (1) intersects the longitudinal axis of lateral frame section (32) orthogonally therewith, which results in its sheer flat end surface (1B'e) projecting away from the circumferential surface of lateral frame section (32), thus creating a clear-cut recession or difference in level (R) therebetween as well. This in turn causes the drawback that the end portion (1B') itself projects past the frame section (32) to present undesired outward projections on the opposite sides of main frame (3). Hence, as shown in FIG. 3, such recession and projection problems not only render uneasy the covering of the framework with the upholding (5, 4 in FIG. 7), but also cause the foam padding layer (4) of upholding to be caught and scratched at (la) and (lb) by the sheer or sharp ends (1B'e) of support wire member (1) and by the sharp flat upper ends (21A) of side brackets (2), respectively, leaving undesired cuts therein. Furthermore, the aforesaid outward projection of end portions (1B'e) on and from the opposite sides of main frame (3) presses the corresponding lateral portions of upholding intensively, resulting in creation of objectionable protuberant points there, which impairs the outer aesthetic appearance of seat back.